1. Field of the Invention
The present relates, in general, to metal fastening techniques and, more specifically, to methods for joining two metal components into a unitary structure.
2. Description of the Art
Various joining processes are available for unitarily joining two metal components or parts together into a unitary structure. Welding, adhesive bonding, and mechanical fasteners, such as screws, are widely employed to fixedly join two metal components or parts together.
Another metal joining technique utilizes a press fit or interference fit wherein one component or portion of one component has an outer dimension slightly larger or oversized with respect to a mating portion, such as a bore or recess, in another component. The two components are urged together to force the oversized portion of one component into the smaller sized portion of the second component to fixedly join the two components together. While effective in certain applications, a press fit or interference fit requires assembly equipment capable of generating and withstanding the high forces or pressures involved in creating the press fit between two components.
In certain applications, the aesthetic appearance of the assembled part requires that screw heads be covered thereby requiring additional assembly steps to finish the part. Similarly, welding two metal parts together along a joint between the two parts, while forming a secure joint, requires subsequent machining steps, such as grinding, to finish the joint to a smooth surface shape.
One example of a two-part metal component structure is a metal golf club head. Metal drivers have replaced older "wood" club head constructions. While it is possible to cast a hollow, one-piece golf club head, such fabrication techniques have presented difficulties in achieving high quality parts at a reasonable cost. Thus, a hollow metal golf club head is typically formed of two cast parts, such as a main body and a separate face plate or sole plate which are then welded together to form the complete golf club head. This is an expensive, time consuming process and requires additional finishing steps to smooth the weld bead to a smooth exterior surface shape on the golf club head.
Similar joinder techniques are employed in metal golf club irons wherein perimeter weights are mounted in recesses formed generally along the bottom edge of the iron to improve club head balance, to lower the center gravity of the club head and to enlarge the sweet spot on the club face. Such weights are mounted in recesses formed in the iron club body and then welded, brazed or soldered into place. Again, time consuming and the additional finishing steps are required to smooth the weld bead between the weight insert and the club body.
What is needed is a joinder technique or methodology for joining two metal component or parts together into a one-piece unitary structure which minimizes assembly steps of the one-piece structure, provides a secure joint between the two metal parts, and minimizes or preferably eliminates after-assembly finishing steps to lower the manufacturing cost of the one-piece structure or component. It would also be desirable to provide such a joinder methodology to the construction of golf club heads provided with a hollow driver configuration or perimeter weighted iron or putter configurations.